U.S. patent number 8,189,488 [Application Number 12/059,650] was granted by the patent office on 2012-05-29 for failback to a primary communications adapter.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Vinit Jain, Jorge Rafael Nogueras.
United States Patent |
8,189,488 |
Jain , et al. |
May 29, 2012 |
Failback to a primary communications adapter
Abstract
Methods, systems, and program products are provided for failback
to a primary communications adapter. Embodiments of the present
invention include receiving, in a driver for a primary
communications adapter and a backup communications adapter, a link
up event for the primary communications adapter; inferring that the
primary communications adapter is capable of receiving packets;
setting the backup communications adapter to idle; and activating
the primary communications adapter. In typical embodiments, the
primary communications adapter includes a plurality of linked
communications adapters comprising an EtherChannel
pseudo-adapter.
Inventors: |
Jain; Vinit (Austin, TX),
Nogueras; Jorge Rafael (Austin, TX) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
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Family
ID: |
35909486 |
Appl.
No.: |
12/059,650 |
Filed: |
March 31, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080178035 A1 |
Jul 24, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10920906 |
Aug 18, 2004 |
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Current U.S.
Class: |
370/245; 370/218;
710/62 |
Current CPC
Class: |
H04L
12/40189 (20130101); H04L 1/22 (20130101); H04L
41/0654 (20130101) |
Current International
Class: |
G01R
31/08 (20060101) |
Field of
Search: |
;370/216-229,235,241-245,248,389,463,465 ;714/2-5
;340/3.43,3.44,825.01 ;710/8,62 ;709/225-229 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
US. Appl. No. 10/777,715, filed Feb. 12, 2004, Banerjee et al.
cited by other .
Lindsay et al. Concurrent Operation of Two Channel Adapters; Jan.
1975; pp. 2479-2483; TDB; US. cited by other.
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Primary Examiner: Ferris; Derrick
Assistant Examiner: Hopkins; Matthew
Attorney, Agent or Firm: DeLizio Gilliam, PLLC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation application of and claims
priority from U.S. patent application Ser. No. 10/920,906, filed on
Aug. 18, 2004, which is now abandoned.
Claims
What is claimed is:
1. A method for failback to a primary communications adapter, the
method comprising: receiving, in a driver for the primary
communications adapter and a backup communications adapter, a link
up event for the primary communications adapter, wherein the link
up event is sent from the primary communications adapter to the
driver, and wherein the link up event is triggered by establishing
electrical connectivity to the primary communications adapter;
determining that the primary communications adapter is capable of
receiving packets; setting the backup communications adapter to
idle, wherein the backup communications adapter receives packets
and drops the packets while idle; activating the primary
communications adapter, wherein the primary communications adapter
receives packets and passes the packets up a protocol stack while
activated; wherein the primary communication adapter further
comprises a plurality of linked communications adapters; and
wherein the plurality of linked communication adapters further
comprise an EtherChannel pseudo-adapter.
2. The method of claim 1 wherein inferring that the primary
communications adapter is capable of receiving packets further
comprises: sending a packet from the backup communications adapter
to the primary communications adapter; and receiving the packet in
the primary communications adapter.
3. The method of claim 2 wherein sending the packet from the backup
communications adapter to the primary communications adapter
further comprises broadcasting an ARP packet to all link layer
addresses on a LAN.
4. The method of claim 1 wherein inferring that the primary
communications adapter is capable of receiving packets further
comprises waiting a predetermined period of time after receiving
the link up event for the primary communications adapter.
5. A system for failback to a primary communications adapter, the
system comprising a computer processor, a computer memory
operatively coupled to the computer processor, the computer memory
including computer program instructions that, when executed by the
processor, cause the system to carry out the steps of: receiving,
in a driver for the primary communications adapter and a backup
communications adapter, a link up event for the primary
communications adapter, wherein the link up event is sent from the
primary communications adapter to the driver, and wherein the link
up event is triggered by establishing electrical connectivity to
the primary communications adapter; determining that the primary
communications adapter is capable of receiving packets; setting the
backup communications adapter to idle, wherein the backup
communications adapter receives packets and drops the packets while
idle; activating the primary communications adapter, wherein the
primary communications adapter receives packets and passes the
packets up a protocol stack while activated; wherein the primary
communication adapter further comprises a plurality of linked
communications adapters; and wherein the plurality of linked
communication adapters further comprise an EtherChannel
pseudo-adapter.
6. The system of claim 5 wherein inferring that the primary
communications adapter is capable of receiving packets further
comprises: sending a packet from the backup communications adapter
to the primary communications adapter; and receiving the packet in
the primary communications adapter.
7. The system of claim 6 wherein sending the packet from the backup
communications adapter to the primary communications adapter
further comprises broadcasting an ARP packet to all link layer
addresses on a LAN.
8. The system of claim 5 wherein inferring that the primary
communications adapter is capable of receiving packets further
comprises waiting a predetermined period of time after receiving
the link up event for the primary communications adapter.
9. A computer program product for failback to a primary
communications adapter, the computer program product disposed in a
non-transitory recordable storage medium, the computer program
product including computer program instructions for: receiving, in
a driver for the primary communications adapter and a backup
communications adapter, a link up event for the primary
communications adapter, wherein the link up event is sent from the
primary communications adapter to the driver, and wherein the link
up event is triggered by establishing electrical connectivity to
the primary communications adapter; determining that the primary
communications adapter is capable of receiving packets; setting the
backup communications adapter to idle, wherein the backup
communications adapter receives packets and drops the packets while
idle; activating the primary communications adapter, wherein the
primary communications adapter receives packets and passes the
packets up a protocol stack while activated; wherein the primary
communication adapter further comprises a plurality of linked
communications adapters; and wherein the plurality of linked
communication adapters further comprise an EtherChannel
pseudo-adapter.
10. The computer program product of claim 9 wherein inferring that
the primary communications adapter is capable of receiving packets
further comprises: sending a packet from the backup communications
adapter to the primary communications adapter; and receiving the
packet in the primary communications adapter.
11. The computer program product of claim 10 wherein sending the
packet from the backup communications adapter to the primary
communications adapter further comprises broadcasting an ARP packet
to all link layer addresses on a LAN.
12. The computer program product of claim 9 wherein inferring that
the primary communications adapter is capable of receiving packets
further comprises waiting a predetermined period of time after
receiving the link up event for the primary communications adapter.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention is data processing, or, more
specifically, methods, systems, and products for failback to a
primary communications adapter.
2. Description of Related Art
EtherChannel is a link aggregation technology that allows several
Ethernet adapters to be aggregated together to form a single
pseudo-Ethernet adapter having increased bandwidth and
fault-tolerance. All the aggregated adapters in the EtherChannel
are typically given the same link layer address and are treated by
remote systems as a single adapter. One benefit of EtherChannel is
that the aggregated adapters have the network bandwidth of all of
their adapters in a single network presence. If a single adapter
fails, network traffic is automatically sent on the next available
adapter in the EtherChannel without disruption to existing user
connections.
Although failure of the EtherChannel is less likely than the
failure of a single Ethernet adapter, failure of the EtherChannel
does occur. To provide failover protection for the EtherChannel,
typically a backup Ethernet adapter remains idle until all the
primary adapters in the EtherChannel fail. When the primary
adapters in the EtherChannel fail, the backup adapter is activated
and administers all Ethernet traffic until at least one of the
primary adapters recovers. When at least one of the primary
adapters recovers, the primary channel is again available for all
traffic and the backup adapter is reset to its idle state.
It is desirable to return Ethernet traffic across the primary
EtherChannel as soon as the primary EtherChannel recovers, because
the EtherChannel has more bandwidth than the backup adapter.
Conventional EtherChannel drivers provide automatic failover to a
backup adapter and dynamic reconfiguration of the primary
EtherChannel. Dynamic reconfiguration of the primary
EthernetChannel typically includes re-establishing electrical
connectivity in the physical layer Ethernet adapter and
initializing the ports connecting LAN segments in the link layer.
When electrical connectivity to the adapter is established the
adapter sends a `link up event` to the EtherChannel driver.
Although there is electrical connectivity to the physical layer
Ethernet adapter, the Ethernet adapter is not capable of sending
packets until dynamic reconfiguration process initializes the ports
connecting segments in the LAN, thereby allowing packets received
through the adapter to be forwarded in the LAN. Failback to the
primary EtherChannel before the primary adapters are capable of
sending packets results in lost packet traffic. There is therefore
a need for improved failback to a primary communications
adapter.
SUMMARY OF THE INVENTION
Methods, systems, and program products are provided for failback to
a primary communications adapter. Embodiments include receiving, in
a driver for a primary communications adapter and a backup
communications adapter, a link up event for the primary
communications adapter; inferring that the primary communications
adapter is capable of receiving packets; setting the backup
communications adapter to idle; and activating the primary
communications adapter. In typical embodiments, the primary
communications adapter includes a plurality of linked
communications adapters that include an EtherChannel
pseudo-adapter.
The foregoing and other objects, features and advantages of the
invention will be apparent from the following more particular
descriptions of exemplary embodiments of the invention as
illustrated in the accompanying drawings wherein like reference
numbers generally represent like parts of exemplary embodiments of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 sets forth a line drawing of a data processing architecture
in which various embodiments of the present invention may be
implemented.
FIG. 2 sets forth a block diagram of an exemplary protocol stack
for data communications between two devices connected through a
network.
FIG. 3 sets forth a block diagram of automated computing machinery
comprising a computer useful in implementing failback to a primary
communications adapter according to embodiments of the present
invention.
FIG. 4 sets forth a flow chart illustrating an exemplary method for
failback to a primary communications adapter.
FIG. 5 sets forth a flow chart illustrating another exemplary
method for inferring that the primary communications adapter is
capable of receiving packets.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Introduction
The present invention is described to a large extent in this
specification in terms of methods for failback to a primary
communications adapter. Persons skilled in the art, however, will
recognize that any computer system that includes suitable
programming means for operating in accordance with the disclosed
methods also falls well within the scope of the present invention.
Suitable programming means include any means for directing a
computer system to execute the steps of the method of the
invention, including for example, systems comprised of processing
units and arithmetic-logic circuits coupled to computer memory,
which systems have the capability of storing in computer memory,
which computer memory includes electronic circuits configured to
store data and program instructions, programmed steps of the method
of the invention for execution by a processing unit.
The invention also may be embodied in a computer program product,
such as a diskette or other recording medium, for use with any
suitable data processing system. Embodiments of a computer program
product may be implemented by use of any recording medium for
machine-readable information, including magnetic media, optical
media, or other suitable media. Persons skilled in the art will
immediately recognize that any computer system having suitable
programming means will be capable of executing the steps of the
method of the invention as embodied in a program product. Persons
skilled in the art will recognize immediately that, although most
of the exemplary embodiments described in this specification are
oriented to software installed and executing on computer hardware,
nevertheless, alternative embodiments implemented as firmware or as
hardware are well within the scope of the present invention.
Failback to a Primary Communications Adapter
Exemplary methods, systems, and products for failback to a primary
communications adapter are now explained with reference to the
accompanying drawings, beginning with FIG. 1. FIG. 1 sets forth a
line drawing of a data processing architecture in which various
embodiments of the present invention may be implemented. The data
processing system of FIG. 1 includes a number of computers
connected for data communications in a network. The data processing
system of FIG. 1 includes a local area network ("LAN") (103). The
network connection aspect of the architecture of FIG. 1 is only for
explanation, not for limitation. Such networks are media that may
be used to provide data communications connections between various
devices and computers connected together within an overall data
processing system.
In the example of FIG. 1, several exemplary devices including a PDA
(112), workstation (104), a laptop (126) and a workstation (102)
are connected to a LAN (103). The PDA (112) connects to the LAN
(103) through a wireless link (114). In the example of FIG. 1, the
workstation (104) connects through a wireline connection (122) to
the LAN (103). The exemplary laptop (126) connects through wireless
link (118) to the LAN (103), and the exemplary workstation (102)
connects through wireline connection (124) to the LAN (103).
Each device in the example of FIG. 1 is capable of implementing
data communications through the communications adapters. Each
device in the example of FIG. 1 is also capable of maintaining at
least one communication adapter as a backup adapter and automatic
failover to the backup communication adapter when the primary
communication adapter fails. In this specification, the term
`failover` means activating the backup communication adapter in the
event the primary adapter or primary adapters fail. Communications
adapters implement the hardware level of connections for data
communications through which local devices and remote devices or
servers send data communications directly to one another and
through networks. The communications adapters installed in the
devices of FIG. 1 are typically capable of being activated by a
communications adapter driver to receive packets and pass them up
the protocol stack or to be set to idle in which case packets are
received but they not passed up the protocol stack. Instead, the
packets are discarded. Examples of communications adapters that may
operate according to embodiments of the present invention include
modems for wired dial-up connections, Ethernet (IEEE 802.3)
adapters for wired LAN connections, and 802.11b adapters for
wireless LAN connections.
Each device in the example of FIG. 1 is also capable of failback to
a primary communications adapter according to embodiments of the
present invention to return packet traffic from a backup
communications adapter to the primary communications adapter. In
this specification, the term `failback` means reactivating, after
recovery, the primary adapter or primary adapters and setting the
backup adapter to idle. Failback to a primary communications
adapter according to embodiments of the present invention operates
generally by receiving, in a driver for a primary communications
adapter and a backup communications adapter, a link up event for
the primary communications adapter; inferring that the primary
communications adapter is capable of receiving packets; setting the
backup communications adapter to idle; and activating the primary
communications adapter.
The arrangement of servers and other devices making up the
architecture illustrated in FIG. 1 are for explanation, not for
limitation. Data processing systems useful according to various
embodiments of the present invention may include additional
servers, routers, other devices, and peer-to-peer architectures,
not shown in FIG. 1, as will occur to those of skill in the art.
Networks in such data processing systems may support many data
communications protocols, such as, for example, TCP/IP, HTTP, WAP,
HDTP, and others as will occur to those of skill in the art.
Various embodiments of the present invention may be implemented on
a variety of hardware platforms in addition to those illustrated in
FIG. 1.
For further explanation, FIG. 2 sets forth a block diagram of an
exemplary protocol stack for data communications between two
devices connected through a network. The exemplary protocol stack
of FIG. 2 is based loosely on the standard Open Systems
Interconnection ("OSI") Reference Model, presented here only for
further explanation. The exemplary protocol stack of FIG. 2
includes several protocols stacked in layers. The exemplary
protocol stack of FIG. 2 begins at the bottom with a physical layer
(208) that delivers unstructured streams of bits across links
between devices. Physical layer connections may be implemented as
wireline connections through modems or wireless connections through
wireless communications adapters, for example. The exemplary stack
of FIG. 2 includes a link layer (206) that delivers a piece of
information across a single link. The link layer organizes the
physical layer's bits into packets and controls which device on a
shared link gets each packet. The Ethernet protocol represents a
link layer protocol. Ethernet addresses are 48 bit link layer
addresses assigned uniquely to linked devices. A group of devices
linked through a link layer protocol are often referred to as a
LAN. An IEEE committee in one popular standard split the link layer
in two sublayers, the first of which, called the MAC layer (for
`media access control`) addresses issues specific to a particular
type of LAN--so that a link layer address is often referred to as a
`MAC addresses.` The present specification, however, is not limited
to any particular kind of LAN and therefore refers to link layer
addresses as `link layer addresses.`
Because each link layer address is unique to a device on a LAN, the
link layer protocol (206) operates generally by circulating all
messages packets on a LAN to each device connected to the LAN. Each
packet includes a destination link layer address. Each device is
then responsible for examining each packet, and discarding those
not addressed to the device, and passing those that are addressed
to the device up the protocol stack for further handling.
The stack of FIG. 2 includes a network layer (204) that computes
paths across an interconnected mesh of links and packet switches
and forwards packets over multiple links from source to
destination. In this specification, packet switches operating in
the network layer are referred to as "routers." The stack of FIG. 2
includes a transport layer (203) that supports a reliable
communication stream between a pair of devices across a network by
putting sequence numbers in packets, holding packets at the
destination until all arrive, and retransmitting lost packets. The
stack of FIG. 2 also includes an application layer (202) where
application programs reside that use the network. Examples of such
application programs include web browsers, email clients, and
others that will occur to those of skill in the art.
Data communications (212) in such a stack model is viewed as
occurring layer by layer between devices, in this example, between
devices (102, 104). That is, data communication between the devices
in the physical layer is viewed as occurring only in the physical
layer, communication in the link layer is viewed as occurring
horizontally between the devices only in the link layer, and so
on.
Vertical communication through among the protocols in the stack is
viewed as occurring through application programming interfaces
("APIs") (210) provided for that purpose. A browser, for example,
operating as an application program in the application layer views
its communications as coming and going directly to and from its
counterpart web server on another device across the network. The
browser effects its data communication by calls to a sockets API
that in turn operates a transmission control protocol ("TCP")
client in the transport layer. The TCP client breaks a message into
packets, gives each packet a transport layer header that includes a
sequence number, and sends each packet to its counterpart on
another device through an API call to the network layer. The
network layer may implement, for example, the well known Internet
Protocol ("IP") which give each packet an IP header and selects a
communication route through the network for each packet, and
transmits each packet to its counterpart on another device by
calling down through its link layer API, typically implemented as a
driver API for a data communication adapter such as a network
interface card or "NIC." When receiving data communication, the
process is reversed. Each layer strips off its header and passes a
received packet up through the protocol stack. Upward passes above
the link layer typically require operating system context
switches.
As mentioned above, devices capable of failback to a primary
communications adapter according to embodiments of the present
invention are generally implemented as automated computing
machinery. For further explanation, FIG. 3 sets forth a block
diagram of automated computing machinery comprising a computer
(134) useful in implementing failback to a primary communications
adapter according to embodiments of the present invention. The
example computer (134) of FIG. 3 includes a plurality of linked
primary communications adapter (167) for implementing connections
for data communications (184), including connection through
networks, to other computers (182). In the example of FIG. 3 the
primary communications adapter comprises a plurality of Ethernet
adapters aggregated together to form an EtherChannel. EtherChannel
is a link aggregation technology that allows several Ethernet
adapters to be aggregated together to form a single pseudo-Ethernet
adapter having increased bandwidth and fault-tolerance. One benefit
of EtherChannel is that the aggregated adapters have the network
bandwidth of all of their adapters in a single network
presence.
The example computer (134) of FIG. 3 also includes a backup
communications adapter (171) for implementing connections for data
communications (184), including connection through networks, to
other computers (182). In the example of FIG. 3 the backup
communications adapter is an Ethernet adapter that is typically set
to idle unless the primary EtherChannel (167) has failed.
Although the exemplary communications adapters of FIG. 3 are
described with reference to Ethernet adapters, this is for
explanation and not for limitation. In fact, other communications
adapters useful in failback for primary communications adapters can
include modems for wired dial-up connections, 802.11b adapters for
wireless LAN connections, as well as others that will occur to
those of skill in the art. The computer (134) of FIG. 3 includes at
least one computer processor (156) or `CPU` as well as random
access memory (168) ("RAM"). Stored in RAM (168) is an application
program (150). Examples of such application programs include web
browsers, email clients, and others that will occur to those of
skill in the art. Also stored in RAM (168) is an operating system
(154). Operating systems useful in computers according to
embodiments of the present invention include Unix, Linux, Microsoft
NT.TM., and many others as will occur to those of skill in the
art.
Also stored in RAM (168) is a communications adapter driver (152).
The communications adapter driver (152) is typically a software
program that controls the primary communications adapter (167) and
the backup communications adapter (171). The communications adapter
driver (152) is responsible for receiving and forwarding packets
through the primary adapter and passing packets up the protocol
stack. When the primary communications adapters (167) fail, the
communications adapter driver (152) of FIG. 3 is capable of
automatic failover to the backup adapter by activating the backup
adapter so that recovery of the primary adapter occurs without
interrupting packet traffic.
The exemplary communications adapter driver of FIG. 3 is also
capable of failback to the primary communications adapter (167)
when the primary communications adapters (167) have recovered.
Failback to the primary communications adapter (167) is typically
carried out by receiving a link up event for the primary
communications adapter, inferring that the primary communications
adapter (167) is capable of receiving packets, setting the backup
communications adapter (171) to idle, and activating the primary
communications adapter (167). A link up event is an event sent by
an adapter to the communications adapter driver triggered by new or
restored electrical connectivity to the adapter.
The computer (134) of FIG. 3 includes computer memory storage (166)
coupled through a system bus (160) to processor (156) and to other
components of the computer. Computer storage (166) may be
implemented as a hard disk drive (170), optical disk drive (172),
electrically erasable programmable read-only memory space
(so-called `EEPROM` or `Flash` memory) (174), or as any other kind
of computer memory as will occur to those of skill in the art.
The example computer of FIG. 3 includes one or more input/output
interface adapters (178). Input/output interface adapters in
computers implement user-oriented input/output through, for
example, software drivers and computer hardware for controlling
output to display devices (180) such as computer display screens,
as well as user input from user input devices (181) such as
keyboards and mice.
For further explanation, FIG. 4 sets forth a flow chart
illustrating an exemplary method for failback to a primary
communications adapter. In the example of FIG. 4, the primary
communications adapter includes plurality of linked communications
adapters that comprise an EtherChannel pseudo-adapter.
The method of FIG. 4 also includes receiving (402), in a driver
(152) for a primary communications adapter (167) and a backup
communications adapter (171), a link up event (404) for the primary
communications adapter (167). As discussed above, a link up event
is an event received in a communications adapter driver during a
dynamic reconfiguration process following failover to the backup
adapter. The link up event represents electrical connectivity to
the adapter. A link up event represents only electrical
connectivity to the adapter in the physical layer of the protocol
stack, but does not guarantee that the ports connecting segments in
the LAN are yet initialized as part of a dynamic reconfiguration
process. Until a dynamic reconfiguration process initializes the
ports, no switch operating in the link layer can receive and
forward packets through the primary adapter. The method of FIG. 4
therefore includes inferring (406) that the primary communications
adapter (167) is capable of receiving packets. One way of inferring
that the primary communications adapter is capable of receiving
packets is carried out by waiting a predetermined period of time
after receiving the link up event for the primary communications
adapter. In such examples, waiting a predetermined period of time
after receiving the link up event for the primary communications
adapter typically includes waiting a predetermined period of time
typical for a dynamic reconfiguration process to initialize the
ports connecting segments of the LAN. As will occur to those of
skill in the art, the predetermined period of time required to
initialize such ports will vary according to many hardware factors
and software factors associated with the system on which the
primary adapter is installed as will occur to those of skill in the
art.
For further explanation, FIG. 5 sets forth a flow chart
illustrating another exemplary method for inferring that the
primary communications adapter is capable of receiving packets. The
method of FIG. 5 includes sending (502) a packet (504) from the
backup communications adapter (171) to the primary communications
adapter (167). In the method of FIG. 5, sending (502) a packet
(504) from the backup communications adapter (171) to the primary
communications adapter (167) is carried out by broadcasting (512)
an ARP packet to all link layer addresses (508, 510, 514) on a LAN
(103). In the method of FIG. 5, broadcasting (512) an ARP packet to
all link layer addresses (508, 510, 514) on a LAN (103) includes
broadcasting either an ARP query or an ARP reply to all link layer
addresses on the LAN.
The method of FIG. 5 also includes receiving (506) the packet (504)
in the primary communications adapter (167). If the ARP packet is
received in the primary adapter (167), then the primary adapter is
capable of receiving packets and is ready to be activated.
In the method of FIG. 5, the packet received in the primary
communications adapter was sent by the backup communications
adapter. This is for explanation only, and not for limitation. In
fact, a packet received in the primary communications adapter may
be sent from any adapter on any computer and the receipt of that
packet confirms that the adapter is in fact capable of receiving
packets and therefore, failback to the primary communications
adapter should proceed.
If the primary communications adapter is capable of receiving
packets, then it is advantageous to activate the primary
communications adapter for receiving packets and return the backup
adapter to idle. Continuing again with reference to FIG. 4: The
method of FIG. 4 includes setting (408) the backup communications
adapter (171) to idle. Setting the backup communications adapter to
idle results in receiving packets through the backup adapter and
dropping the packets. Packets received through the idle backup
adapter are not passed up the protocol stack and therefore are
discarded.
The method of FIG. 4 includes activating (410) the primary
communications adapter (167). By activating (410) the primary
communications adapter (167), packets received through the primary
communications adapter are passed up the protocol stack thereby
effecting data communications.
It will be understood from the foregoing description that
modifications and changes may be made in various embodiments of the
present invention without departing from its true spirit. The
descriptions in this specification are for purposes of illustration
only and are not to be construed in a limiting sense. The scope of
the present invention is limited only by the language of the
following claims.
* * * * *